D-Guard
2
24
10.
Commissioning
Once D-Guard-2 has been mounted and electrically connected, it must be commissioned.
Commissioning of the monitoring system to which D-Guard-2 is connected is beyond the scope of this manual
since specific methods will depend upon the details of the installation. There are nonetheless, common
considerations to make in the processes of testing newly installed gas detectors. The following is a
recommended sequence of checks to assist in ensuring correct operation of D-Guard-2.
Commissioning must be carried out by suitably trained personnel operating under permitted site
conditions. Incorrectly commissioned detectors could cause the monitoring system to become non-
operational in its intended manner, resulting in potentially harmful situations.
Performing commissioning using non-approved or site inappropriate equipment could create a hazard
situation and increase the risk of injury.
10.1.
Installation Verification
The specifics of performing the steps listed below will depend on the nature of the installation and any /all
conditions governing the installation site or area. Before each of the steps are followed, it is essential to ensure
that appropriate measures and precautions have been taken to reduce the likelihood of a hazardous situation
being created and that the risk of triggering a dangerous event is not increased (e.g. ignition of combustible gas).
It may not be possible or practical to carry out every one of the steps given below.
If in doubt regarding the methods of commissioning, or possible outcomes of carrying out
commissioning steps, consult an appropriate supervisor for advice or training. Do not conduct
commissioning on a system unless fully competent to do so and only with the knowledge that it is
safe to do so.
Ensure that power to the detector is isolated at the controller side of the installation.
Visually check that detector mounting conforms to information given in this manual.
Check that all electrical connections within the detector(s) are correct per this manual.
Conductors should be marked and coded at each end for easy identification.
Check that the power supply feeding the detector is of an appropriate type and that it is matched to
the detector’s requirements.
Switch on the system power and check that the supply voltage at the detector power terminals meets
the requirements given in the detector specification table at the end of this manual.
Newly powered up detectors can draw full scale current for the first few minutes of operation whilst
the gas sensing cell settles. This will present a greater than normal load demand on the power
supply. An under-rated power supply and/or poor cabling can create voltage drops between the
power supply and the detector. This situation is made worse when numerous detectors share the
same cable run.
Once powered (power supplies correct and stable), allow the system to settle for at least 1 hour.
The detector display should be on. Displayed information includes gas type and range, status
messages and gas reading. The gas reading should be showing either a stable zero or a value
representative of the sensor cell as it stabilises. Initially this may be a full scale or negative reading.
The status message may be indicating a sensor low fault, or over-scale message. These are normal
conditions that can be expected for the first few minutes after power up. At the end of the 1 hour
period however, the detector display must be indicating zero or close to zero and status messages
must indicate that there are no faults or alarms.
